Abstract:

With sodium carbonate as an auxiliary agent to decompose the mullite and aluminosilicate glass phases of  high-alumina fly ash from a coal power plant in northern China, the aluminum hydroxide was prepared by sintering the raw materials at intermediate temperature, acid-leaching to separate silica and alumina from the sintered materials, adjusting the pH value of the filtered aluminum chloride solution ranging from 5 to 6 to purify the filtrate, and acidifying by entrance of CO₂. XRD, SEM and chemical analysis methods were used to characterize the aluminum hydroxide product. The experimental results indicated that the prepared aluminum hydroxide, with granular size around 200 nm in diameter, was spherical particles in shape, and satisfied with the China National Chemical Standard GB/T4294—1997. These results demonstrate that this technique is industrially feasible to utilize this sort of highalumina fly ash as a potential alumina resource in the future.

Key words: high-alumina fly ash, aluminum hydroxide, alumina resource